Powder igniter



1954 w. P. SPAULDING POWDER IGNITER Filed July 24, 1944 United StatesPatentO POWDER IGNITER Wallace P. Spaulding, Cumberland, Md., assignorto the United States of America as represented by the Secretary of WarApplication July 24, 1944, Serial No. 546,336

8 Claims. (Cl. 60-35.6)

This invention relates to an igniter for igniting the propulsion charge'of a rocket projectile.

Prior art igniters utilized to ignite a rocket propulsion chargecomprising a stack of disks or washers of powder stnmg on a rod andaxially supported within a rocket motor of a rocket projectile have notbeen very satisfactory. This was due primarily to the inability of suchigniters to obtain uniform ignition. It is appreciated that in this typeof propellent assembly it is extremely difiicult to obtain uniformignition, and particularly simultaneous ignition, of the entire area ofthe contiguous surfaces of the disks. One form of prior art igniterutilized a plurality of muslin bags containing black powder which wereelectrically fired by a squib. Such bags extended longitudinally of thechamber and were positioned around the outer periphery of the propellentassembly. Obviously to obtain complete ignition of the propellentlaminations a sizable quantity of black powder had to be used, resultingin relatively high ignition pressures with consequent damage to thepropellent charge. Further, uniform ignition could not be consistentlyattained because the direction of flow of the hot gases liberated by theblack powder is generally axially of the combustion chamber thusminimizing the propagation of the flash radially between the disks.

Accordingly, it is an object of this invention to provide an igniter fora powder charge to uniformly and simultaneously ignite the entirecharge.

A particular object of this invention is to provide an igniter touniformly and simultaneously ignite a rocket propulsion chargecomprising a laminated stack of disks or washers of propellent powder.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view of a rocket projectile embodyingthis invention.

Fig. 2 is a detailed view showing the construction of one form ofigniter.

Fig. 3 is a view similar to Fig. 2 showing an alternate type ofconstruction utilizing longitudinal strips of combustible material.

Fig. 4 is a cross sectional view taken along the plane 4 4 of Fig. 3.

While it will be apparent to those skilled in the art that thisinvention has application generally in all types of rockets, it isparticularly well adapted for use 1n rockets employing laminatedpropellents and is so disclosed.

Referring to the drawing wherein like characters refer to similar partsthere is shown a rocket projectile embodying this invention. Acylindrical motor chamber 1, one end of which terminates in a nozzle 2of well known Venturi construction, is provided to house the elements ofthe projectile. An ogival head 3 is secured to the forward end of rocketmotor 1 as by threads 4, and contains the pay load which may consist ofa high explosive, a chemical grenade or the like. A propellent charge 5comprising a plurality of disks or washers 6 of suitable propellentmaterial is axially mounted withm rocket motor 1 by a tube 7, threadedat each end, which is passed thru the single axial perforation 8 in eachof the disk-like powder grains 6. Tube 7 is screwed into an axialthreaded hole 9 provided in the base of head 3. The stack of individualpowder grains or disks 6 strung on the tube 7 are preferably retained onsuch tube by a wishelr 10 and a nut 11 screwed onto the free end of tu eThe laminar or contiguous surfaces of each disk or washer 6 ofpropellent material are more or less screened from any type of igniter.However, it is apparent that an ignition system located within thecenter of the charge would be best adapted to effect ignition of suchcharge.

An igniter embodying the features set forth above is shown in Fig. 1.Such an igniter is formed by wrapping tube 7 spirally with a layer ofcombustible tape 15 such for example as paper or cellophane, which has acoating of adhesive material 16 applied to the surface facing outwardlywith respect to the surface of the tube 7. Each successive turn of thetape is preferably arranged to overlap somewhat and thus secures itselfin the spiral form. Tube 7 with its adhesive surface 16 is then immersedin a container (not shown) of finely granulated black powder 17. Thepowder grains 17 adhere to the adhesive outer surface of the tape andprovide a complete coating of the powder about tube 7.

To assemble the tube 7 in the rocket motor 1, the propellent disks 6 arecarefully strung on tube 7. An electrical squib 13 preferably shaped inthe form of a ring is suitably secured to the forward end of tube 7 andis arranged to be fired by the lead wires 14. Upon ignition of squib 13the black powder coating 17 is ignited which acts as a quick match tosubstantially simultaneously and gnilformly ignite the contiguoussurfaces of the powder is s.

As illustrated in Fig. 2, a second wrapping of combustible tape 18 maybe applied over the black powder coated first Wrapping with the adhesivesurface 19 inwardly disposed. Such a construction obviates thepossibility of rubbing off any of the adhering powder grains duringassembly in the projectile. A further modification in the constructionof the igniter, illustrated in Fig. 3, comprises suitably securinglongitudinal strips 15' of combustible material to tube 7 having afiixedthereon a layer 21 of igniter mixture secured by a suitable adhesive.Such longitudinal strips 15 may also be wrapped with ag exterior layerof combustible tape 18 as described a ove.

Thus it is readily apparent that an improved igniter for simultaneousand uniform ignition of a propellent charge for a rocket is herebyprovided. As only a comparatively small igniter charge is utilized nohigh ignition pressures are built up within the rocket motor and hencedamage to the propellent assembly is avoided.

I claim:

1. In combination, a powder charge having an axial recess, a tubularmember extending thru said recess, a tape wrapped around said member, anadhesive coating on the exterior of said tape and a plurality of powdergranulations secured to said adhesive coating.

2. An igniter for a powder charge comprising a tubular element, a tapehaving an adhesive coating on at least one side, said tape beingspirally wrapped on said tubular element in overlapping relation withsaid adhesive coating on the exterior, thereby securing said tape in itsspiralled shape, and a plurality of powder granulations secured to saidadhesive coating.

3. An igniter as in claim 2 and a second combustible tape having anadhesive coating on one side thereof spirally wrapped over said powdergranulations with its said adhesive coating on the inside.

4. An igniter for a powder charge comprising a tubular element, aplurality of strips of tape secured to the surface of said tubularelement, a coating of adhesive on the exposed surface of said strips oftape and a plurality of powder granulations secured to said adhesivecoating.

5. In a rocket motor, a propellent charge comprising a stack of powderwashers, a support rod passing axially thru said stack of powder washersto thereby support said stack within the motor, a tape wrapped aroundsaid support rod and lying intermediate said rod and said powderwashers, a coating of an igniter composition on the exterior of saidtape and an electric squib supported on said rod and arranged to ignitesaid igniter composition.

6. In a rocket motor, a propellent charge comprising a stack of powderwashers, a support rod passing axially thru said stackof powder.washersm thereby support said stack Within the motor, a tape wrappedaround said support rod and lying intermediate said rod and said powderwashers, an adhesive coatingon the exterior of said tape and a pluralityof powder granulations secured to said adhesive coating and anelectrical squib constructed in annular form and mounted on said supportrod in position to ignite said powder granulations.

7. in a rocket motor, a propellent charge corriprisinga stack of axiallyperforated discs, at supporting member disposed axially of said'propellent charge and a coating of igniter material applied to asurface of said supporting member which is adjacent said propellentcharge.

8. The manufacture of an igniter for a laminated rocket propellentadapted to be supported by being strung on a central rod, comprising thesteps of wrapping spirally on said rod a strip of tape having anadhesive surface, the adhesive surface being outward relative to the.surface of said rod, overlapping the spiral wrappings of adjacent.turns. of said tape. so that. said adjacent. wrap.- pings will be joinedby said. adhesive, and immersing the outer surface of said tape into agranulated igniter compound, whereby the granulations will adhere tosaid adhesive surface.

References C itedj'in tlie'fi le of this patent UNITED STATES PATENTSNumber; Name" Date 1,812,010 McBride June 30, 1931 1,897,948 Young Feb.1'4,.1'933 2,094,552 Lowy Sept. 28, 1937 2,239,051 Pearsall et al. Apr;22, 1941 FGREIGNJ PATENTS:

Number Country Date 207,540. Switzerland Nov. 15., 1939 503,078 France:Mar. 8,.1920

